This invention relates to systems and methods for marking and coding objects and, more particularly, to systems and methods for optically coding objects such as textiles, linens, garments, documents and packages.
A class of industrial problems exists in which a large number of items must be separated, identified, counted and sorted. One example is the textile service industry, wherein soiled garments or linens are returned in large unsorted groups for cleaning and sorting. Present day means for solving this problem cover a broad spectrum. One solution uses manual workers who sequentially sort amongst the many items, picking single items manually and identifying the items visually. This solution is unsatisfactory because it is both slow and expensive, due to the high reliance on manual labor.
There are also numerous coding and sorting applications in the multi-billion dollar textile services industry whose requirements are not efficiently met by bar codes or radio frequency identification (RFID). A particularly challenging problem is the sorting of flat goods such as napkins, tablecloths, towels and bed linen items. These items, which range in size from very small to large, are presented in distorted orientations and undergo severe washing and ironing cycles. These are just some of the technology barriers to accurate machine identification and automated counting and sorting of flat goods and bulk garments. The lack of a viable coding and sorting solution for this segment of the textile services industry has resulted in high labor costs, lack of stock control, and reduced profits.
Thus, a technique that provides for the machine readable marking of rental textiles is important for inventory control at commercial laundries and other installations where large quantities of similar-looking materials must be handled in a high speed manner. Currently, only a small fraction of the rental textile industry uses machine readable coding. Most coding currently used to uniquely identify a rental textile item is simply text printed on a heat-sealed label attached to the item, and requires the presence of a human operator.
There are several reasons why the textile rental industry has only slowly adopted machine readable identification technology. Historically, the only available machine readable marking schemes for textiles were bar-codes and radio-frequency ID (RFID). Bar codes are the most commonly available type of machine readable marking in use today. However, tests of identification systems in actual laundries have shown that bar coding is not a robust coding technology on textile items. Bar codes are highly susceptible to degradation through both soiling and wear. Furthermore, due to the precise spatial information required for a bar code (line width and spacing), any warping of the label (almost assured on a fabric substrate) can result in high reading error rates. Finally, bar codes require line-of-sight and (generally) a specific orientation with respect to the detector, both of which are difficult conditions to satisfy under typical large scale laundry conditions.
In contrast, the radio-frequency ID technique does not suffer from the line of sight and soiling problems associated with bar codes. However, RFID remains expensive, both from initial cost and associated maintenance costs, and therefore is normally not economical for the rental textile industry. Furthermore, RFID tags have a tendency to exhibit cross-talk when they are in proximity to one another, which can preclude their use on closely-spaced sorting conveyors.
It can be appreciated that a need exists for a technology that has the ease of use and the low cost associated with bar codes, and yet is more robust and tolerant of the conditions found in large scale commercial laundries and other similar environments, such as large scale document and package handling facilities.
In U.S. Pat. No.: 5,881,886 xe2x80x9cOptically-Based Methods and Apparatus for Sorting Garments and Other Textilesxe2x80x9d one of the inventors of this patent application has described various methods and apparatus that also address the problems referred to above.
It is a first object and advantage of this invention to provide an improved optically based system and method for encoding information onto objects, and for subsequently sorting or otherwise processing the objects using the encoded information.
It is a further object and advantage to provide a photonically encoded label wherein information concerning an object is encoded in both the spatial and wavelength domains.
The foregoing and other problems are overcome and the objects of the invention are realized by methods and apparatus in accordance with embodiments of this invention.
The teachings of this invention provide embodiments of a Multi-Spectral Imager and the application of same for the marking and coding of, for example, textiles, linens, garments, documents and packages for high-speed machine identification and sortation. Specific uses include, but are not limited to, garment and textile rental operations, laundry operations, and the postal and mail sortation of documents and packages.
The teachings of this invention are directed towards providing methods and apparatus that are used to identify items via information encoded within an applied mark, as well as a novel mark reading/decoding scheme. The teachings of this invention are multi-faceted, and encompass a method of printing fluorescent marks on an item, such as a heat-sealable label, to generate a unique identification number or indicia, as well as a reader system for reading applied marks. The reader system includes an illumination source that excites the fluorescent marks in combination with a color sensitive device, such as a camera, which is xe2x80x9cblindxe2x80x9d to the illumination wavelength but which can discern the fluorescence color and a relative spatial order of the fluorescent marks.
A method is disclosed for encoding information onto an article, and includes steps of (a) expressing the information as a multi-digit number; and (b) encoding the number as a plurality of regions that are disposed in a predetermined linear sequence. Each region emits one of a plurality of predetermined wavelengths comprising a set of wavelengths. A further step applies the plurality of regions to the article by printing the plurality of regions onto a label using a plurality of different fluorescent inks, and then affixing the label to the article, such as by a thermal process.
To readout the encoded information, the method further includes steps of (c) illuminating the plurality of regions with excitation light; (d) detecting a plurality of resulting wavelength emissions from the plurality of regions; and (e) decoding the number from the plurality of resulting wavelength emissions and their location in the linear sequence.
The article can be identified from the decoded number, and a future path that the article takes can be controlled based on the decoded number. As an example, a controller can select a type of washing that the article will receive, and/or a storage location for the article can be determined, based on the decoded number.